You appear to have 2 virtual machines in your environment with the name Server01 - one is in the discovered virtual machines folder

This folder can be seen in the vSphere Client, although you may have to change the view to see it.

EDIT: I believe this discovery is something that happens within VMware itself if a virtual system is found in a datastore that is not already registered into the VMware environment. Backup Exec then just displays (and in this case automatically includes) what it finds in VMware.